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Mast Cell Cancer – Winger’s Diagnosis and Timeline

My 11 year old Golden Retriever, Winger, had emergency surgery to remove a lump on his head that started bleeding uncontrollably. Results came back from the histopathologist indicating the lump removed was a mast cell cancerous tumor. As I research and read about this cancer, I will add information and resources to this page.

What is mast cell cancer?

Mast cell cancer is the cancer of the mast cells. Mast cells are normally found in the tissues of the body. From a dictionary, the definition of a mast cell is ” a large cell that occurs especially in connective tissue and has basophilic granules containing substances (as histamine and heparin) which mediate allergic reactions”.

Mast Cell Cancer occurs mostly in dogs, sometimes in cats, and very rarely in humans.

Mast cell cancer is also referred to as histiocytic mastocytoma, mast cell sarcoma, and mastocystosis (when there is systemic involvement).

How to recognize a mast cell tumor

From what I’ve learned today, mast cell tumors don’t have a common look. They can be big or small. They are most often found in the skin, but can also be found on the spleen, liver, or in the bone marrow. Common places in the skin are on the main body, hind legs, or head and neck. Now that I have read more, Winger’s lump had warning signs. It changed size often. It would swell up and shrink down again. If any of your dogs lumps do this, insist on your vet checking them! Winger’s lump was pea-sized for a long time – a year or more? Then it started changing size and eventually was the size of a ping pong ball when it started bleeding and required emergency removal.

Grading of Mast Cell Tumors

Mast cell tumors are graded between 1 and 3, with 3 being the worst. Grade 1 tumors are the least aggressive and are are well defined. Grade 3 are are very aggressive and poorly defined. Grade 2 is somewhere in between.
Winger’s was graded a 2a, however the vet said it was on a scale from 1 to 4 (4 being the worst) so I am unsure how this compares to all the literature I have read today which have all cited the 3 grade ranking system.


Care is needed when handling mast cell tumors. Even feeling them through the skin, or taking a needle aspirate, can cause the tumor to release large amounts of histamine that causes redness, itchiness and swelling. Some dogs are treated with Benedryl to control the itchiness and allergy symptoms from the release of histamine from the mast cell tumor.

Prednisone is often prescribed to reduce the inflammation of the tumor. Prednisone has several side effects on the dog, including an increase in drinking and urination, and a change of appetite. However, it is inexpensive, relatively safe, and effective in reducing the inflammation. Sometimes a veterinarian will prescribe prednisone prior to surgery to reduce the inflammation, thereby reducing the size of the tumor that needs to be removed.

Surgical removal is the most common treatment. Although mast cell tumors normally feel like one solid lump, the surrounding tissue is also cancerous. This is why wide margins (3-5 centimetres in all directions) are imperative to removing all the affected tissue.

Even if margins are clean after surgical removal, meaning all the tumor was removed, re-growth of the tumor is reportedly as high as 50%.

If surgery is not an option, due to the dogs health or location of the tumor, radiation is a possible option. Mast cell tumors are very sensitive to radiation therapy. Radiation is also a common option when surgery did not successfully remove all of the tumor. Radiation is not a good choice if the cancer has already spread to other organs.

Mast cell cancer rarely spreads to the lungs. Instead it affects other areas of the body. When the cancer has spread, the signs you may see include loss of appetite, vomiting, bloody vomit, diarrhea, abdominal pain, dark or black feces, itchiness, lethargy, anorexia, irregular heart rhythm and blood pressure, coughing, labored breathing, various bleeding disorders, delayed wound healing, enlarged lymph nodes. When a dog dies from mast cell cancer, it is usually from the loss of life quality from the constant vomiting and diarrhea.

Prognosis varies greatly depending on the location of the tumor, and its stage of development. Tumors located in places other than the skin are usually more aggressive. Dogs showing systemic signs, listed in the above paragraph, or dogs who experience a regrowth of their tumor, have a poor prognosis.

Risk Groups

Mast cell cancer affects many dog breeds. Golden and Labrador Retrievers are common victims, as are Boxers, Bulldogs, Boston Terriers, Bull Terriers, Beagles, Bullmastiffs, Dachshunds, English Setters, Fox Terriers, Schnauzers, American Staffordshire Terriers, and Weimaraners. A very interesting quote “There is some suggestion that mast cell tumor development may be associated with golden/red coat color and with chronic immune over-stimulation that occurs in dogs with allergies or other inflammatory conditions.” (source) Interestingly enough, Winger has always had allergies and food intolerances and hotspots.

Resources: Links and Photos

Winger’s Tim


Very sadly, I lost Winger to mast cell cancer on September 15th, 2005. He was exactly 11 years and 10 months old. I couldn’t find any full timeline stories on the internet, so I would like to put together Winger’s in hopes that it will provide information to someone who needs it. Most of the following is excerpts from posts I made on the message forum. As I think back, I believe Winger had mast cell cancer for close to 2 years, perhaps longer than that, and we had no idea. I’ll share details of his health for his last year.

February 8, 2005
 – Peeing in the house – No, not a puppy, but a senior. I knew one of my dogs has been peeing in the house occasionally during the night over the last couple of months but I assumed it was Surf because she eats too much snow and after she eats tons of snow she seems to pee inside and not realize it. But since Surf stays in her crate during the day and there we haven’t had a decent snow fall in a couple months, I think we have a problem because I got home from work today and stepped in a puddle on the carpet again (always right where I step too!).
So it’s Winger – mostly during the night, but he did while I was at work today. He is 11 years old, great appetite, loves playing, active, doesn’t seem sick – is this a senior thing?
Just over a year ago he had a problem – he wasn’t concentrating his urine and was drinking a ton and then peeing for long periods of time. We did a bunch of tests and everything was fine, he just wasn’t concentrating his urine. In case it was an infection, she prescribed an antibiotic and it worked. This seems a bit different. Although he has consumed large amounts of water for a couple years now.
He was always the dog who would seem to hold it for ever. And he’d definitely wake me up at night if he had to go out. Either I’m sleeping really deeply or he isn’t trying to wake me up.
I guess I better make a vet appointment for him. I don’t want to wake up every night and come home for lunch to let him out, but I suppose I don’t have a choice. Crating him doesn’t seem fair.

April 16, 2005
 – Poor Winger has had a rough couple of months. If you remember, he had been peeing in the house but the vet diagnosed him healthy. He continues his obsession with water, but luckily there hasn’t been any accidents in the house in quite awhile. I tried to limit his water, but then he gets way worse and when I give him water, he’ll drink the entire bowl, no matter what size it is. He just starts to drink and doesn’t stop – a few times a day I find myself telling him to stop drinking after he’s been at the water bowl for a couple minutes straight.
Then he had a huge hot spot on the side of his back leg, in between his ankle and knee. He’s never had one there before and I wonder if he hurt himself first and then chewed it into a hotspot – he’s a big chewer – or what. Because of where it was he was limping badly. He’d try to gallop up the stairs into the house, but his back legs wouldn’t keep up and he’d get his back legs pinned up under him and slide back down – so hard to watch! I rushed out a few times to catch him. Finally that is healing and now it’s something new!
You know those small lumps and bumps these goldens get with age (Winger is 11). He’s had one on the top of his head for a few years and maybe once a year or so it seemed to bother him and he’d rub his head and it would swell, but within a few days it would return to normal. Well yesterday it was the size of a ping pong ball! and it’s really itchy for him. Now it’s weeping badly – maybe from rubbing and scratching or maybe just because it’s a sebacceous cyst and it ruptured. Not pretty!
But Winger is always a happy old gentlemen. He never complains and just goes about life doing whatever his body will allow him to do on that particular day. Some days his arthritic hip displasia ridden hips will allow him to leap on the bed, and somedays, just not even close. He never stops smiling though. I’m planning on taking them out to the retriever club grounds for a good run (and swim without a doubt) today. Then I’ll give Winger a good bath and rinse off his leaking head.
Here is a photo of him from a couple days ago – you can see the growing bump on the back of the top of his head!

Winger - April 2005

June 27, 2005
 – 7pm – Winger’s had this bigger-than-a-ping-pong-ball sized hard rock growing on top of his head for quite awhile now. A couple months ago he had his the top of his head shaved when he rubbed it enough to develop into a huge hotspot.
Today it has finally decided to burst. It’s leaking blood and fluid all over the place. Every two minutes I have to wipe his head and it soaks up a couple kleenexes as it runs down the back of his head and under his ear. I tried to leave him outside since it’s a bizillion degrees here but the bugs kept sitting on it! I’m tempted to try to fashion some sort of bandage for his head, but I really want this thing to drain and go away!
Both of my dogs have had these now. This is Winger’s second. Both had one on the side of their upper rear leg and when they finally drained they never came back. I sure hope this is the case with this one! (Last time Surf’s broke and leaked on my good friends WHITE duvet when we were visiting! ahhh!)
8pm – Okay he’s bleeding more and more, pouring out, and it’s not the fluid tinged stuff anymore. I think we’re off to see an emergency vet!
9pm – Winger’s having emergency surgery tonight. The vet couldn’t get the bleeding to stop. We applied pressure for an hour, cauterized it, still kept bleeding. Surgery is so scary for a dog who is 11.5, but we ran out of options. He doesn’t think it’s a sebaceous cyst because of all the blood, unless Winger rubbed it on the fence or something and injured a blood vessel. He plans to completely cut the big lump out and since Winger has lots of extra skin, it shouldn’t be a problem to sew him back up. I had to leave him there. I’m a mess. I’ll post when I hear how the surgery went.
10pm – Winger’s out of surgery and is sleeping it off. Everything went well. The vet said they encountered some blood vessels that they had to tie off, and some other medical lingo that went way over my head. They’ll watch him over night. He said with older dogs it takes longer for them to metabolize the medications so he expects him to be very dosey all night. I’ll call tomorrow morning to see how he is and hopefully he’ll be home in the afternoon.

June 28, 2005
 – Winger is home and doing well! His eyes seem glassy to me, and he was super thirsty when he came home, but he looks good. He has a bit of a cough probably from the tube down his throat irritating it the vet said. His stitches will stay in for 2 weeks. He has internal and external stitches. The incision is about 4 inches long. The emergency vet visit, surgery, overnight stay, a week of antibiotics – it was only $400 with tax. VERY reasonable! I thought it would be 4 times that, especially since it was after hours. I opted to pay an extra $98 to send it away to the pathologist. Then if it was something bad, the report will say if they got it all out or not. The vet wasn’t sure what it was. I wasn’t going to send it away, but I guess it would be nice to know. I’ll get the report back by the end of next week.
Here are 3 photos I just took of his head, if you like to look at such things:

stitches3 stitches2 stitches1

July 6, 2005
 – Winger went to the vet today to get some fluid drained from under his incision. He’s healing really well, probably because I’ve made him keep the cone on.
The results are back from the histopathologist. It was a mast cell tumor (cancer). They are rated on a scale from 1 to 4, with 4 being the worst. His was a 2a. The analysis of the margins show that not all of it was removed.
The vet said if it was a 4 he’d re-operate right away, but being where it is, it would be difficult to get wider margins because there is only so much skin available on the back of the head. For now he suggests we wait and see if it grows back. Winger is 11.5 so that plays a factor as well.
I had the vet take a sample of small lump Winger’s had for a long time in the skin over his shoulder. I should know tomorrow if it is the same thing. If it is, it’ll be much easier to remove when it’s small and not large and bleeding so bad as this one was.

July 12, 2005
 – Winger got his stitches out today and is cleared for swimming! Unfortunately it’s WAY too hot for swimming, they’d die in the truck on the way there or back! I suspect he’s also enjoying life without the cone on his head anymore! (I’d swear he was walking into my legs with that thing on purpose)
The vet said to expect some irritation and inflammation, especially at the ends of Winger’s healing incision for 4-6 weeks as the internal stitching gets absorbed. After that, if the cancer cells left decide to grow another tumor, it will most likely be found within the incision, because any of those cancerous cells that were left behind will be located there. So I’ll keep a close eye on it!
This wasn’t my normal vet, but the one who answered the emergency page 2 weeks ago when Winger’s head was bleeding so bad. They are so nice, and I still can’t get over the price. $400 for the late night surgery, drugs, a week’s prescription, an over night stay, etc. and they haven’t charged us for last week when he got some fluid drained, or today for getting his stitches off. Very reasonable!
OH and the good news, the bump I had tested on his shoulder is just a sebaceous cyst. Nothing to worry about!

August 2, 2005
 – Part of dealing with a dog with cancer must be anger, because I’m angry. Angry with some little bumps that are trying to take over my boy.

Winger has 3 bumps growing back on his head now. He had the mass cell tumor removed there on June 27th. One is growing back where the other one was, and there is one an inch or so behind each of his ears. They are just pea sized, but are growing each day. I’m thinking that another surgery isn’t possible because there just isn’t enough skin on the back of his head to allow them to carve out 3 more bumps, since they need to take 3-5cms for clean margins. If they do a surgery, I imagine his ears will probably he stretched to the back of his head!
This morning I woke up to him shaking his head non-stop. He has a hot-spot IN HIS EAR! Not on the flap, but the inside of his ear – all red, wet, and stinky. I had trimmed his ear yesterday and noticed it was red, but overnight it turned into a mess! So I’ve cleaned it up a bit and put some hydrocortisone ointment on it. Then I gave him benedryl. His head shaking seems to have slowed down.
He is otherwise doing great! He’s a healthy dog with so much fun and play in him. The cancer hasn’t spread to any organs, just these bumps. But they release histamine which has brought back his excessive drinking and runny eyes.
I don’t know what my options will be now. Hopefully the vet will be able to see us today. I have read of some dogs going on prednisone to control the growth of the mast cell tumors if they can’t do surgery.

August 3, 2005
 – Winger had his vet visit today. The vet confirmed through a fine needle aspirate that two of Winger’s new bumps are mast cell as well. The vet thinks his inflamed ear and gooey eye are caused by the tumours and the gunk they release into his system. So he decided to give him an injection of DEPO-MEDROL which is a steroid. The hopes are that it will slow the growth of, and hopefully shrink the new tumours and it should definitely get his other symptoms under control. He also gave me an ear ointment in the meantime.
The vet also noticed Winger’s cough, as did the vet who did the surgery a month ago. I think he’s had it for months – usually when he’s panting. The vet said I might want to do a chest x-ray at some point. Maybe it’s just from the histamine and whatever else these tumours secrete. I think if he can cancer in his lungs he’d be long gone?
The vet said an option is to take him to a teaching vet hospital and they could remove these new tumours and do radiation, but Winger’s just a few months shy of 12 years old, and I don’t see this route as a likely plan.
For now we’ll see how this injection works. The vet said I might hope to see the new bumps start to shrink in a week or so.

September 2, 2005
 – Winger went back to the vet today for a check-up. The steroid shot he got four weeks ago didn’t seem to help, and now he has 4, maybe 5 now, fast growing mast cell tumours on his head. He’s been coughing a lot lately and when he scratched the two tumours behind his ears and they started to bleed a little, I thought for sure I’d have to put him down this weekend.
Luckily Winger has NO idea he has cancer. He is a happy eleven year old, who is still a retrieving fool who is loving life as he always has.
The vet consulted his text books and decided on prednisone. I could use a chemotherapy drug but I don’t want to go that route, and none of the research I read suggested it’s that successful on mast cell tumours. So Winger was put on 50mg/day of prednisone for the next 3 weeks. The hope is that it will reduce the swelling of the tumours. We’re also trying to manage his other symptoms. Mast cell tumours release histamine into the body, so Winger always has runny eyes and he has a cough. The vet said I can give him 75 mg of benedryl 3-4 times a day if I need to. That sounds like a massive amount because sometimes I have him 2 pills and he acts a little drugged, but not itchy! So I’ll probably start off easy if he needs it. I just don’t want him to scratch a lump – although the vet doesn’t think they’ll bleed uncontrollably like the one he had removed at the end of June.
I don’t want him to be sick and suffering, so I’ve cried a lot this week, but decided when he starts to get sick, I’ll end it. But not until then. I mean no offense to anyone, but through all the research and reading about canine cancer this summer, some people go to extreme lengths to keep their dogs alive, even while their dogs are suffering. I know this cancer will end Winger’s life, so as long as he’s relatively well, we’ll treat the symptoms. I certainly couldn’t look into his eyes today and say goodbye, he’s a crazy maniac. Is hyperactivity a side effect of a high prednisone dose? I’ll have to research that, because he just raced up my back steps on the deck like he was a pup – he’s not feeling those arthritic hip displasia hips today!
I’m also deciding on his diet. Mast cell tumours spread to the stomach and GI tract and spleen. Prednisone can cause intenstinal problems. His immune system is out of whack. I just don’t think raw meat is a good idea anymore. I know many people never switch to raw until their dog gets cancer, but I think switching to the Duck and Potato kibble that he tolerates well, with his normal dose of fruits and veggies, is probably going to be my chosen route. Many mast cell dogs are treated with a combination of benedryl, prednisone and tagamet – tagamet to counteract the stomach/intenstinal problems.

September 15, 2005
 – I woke up this morning to find fresh blood in hallway. The tumor behind Winger’s left ear had ruptured in 3 places and was bleeding quite a bit. I had decided long ago not to put him through another surgery, however I doubt he was healthy enough to have one anyway. I spent the day with him, his head bleeding the entire time, and I said good-bye in the vet’s office at 5pm.
I had noticed that his head was changing. On his head, above his eyebrows, there was an area on each side that seemed really sunk in. Upon looking at photos I took this last day, I can see that it looks like the bones on each side of his head there were very stretched. I wonder if he had more tumours in his head. The tumours on the outside of his head had grown so big in the last few weeks. The prednisone hadn’t seemed to slow them down at all. Three of them were nearing the size of a golf ball again.
I guess I’ll never know what would have happened if one of the vet’s we had visited in the last 2 years had biopsied Winger’s first bump on his head. It could have been removed so long ago, and maybe it would never have come back. I’ll never know. Part of the reason all his new lumps came and grew so fast is probably because the first tumour was left to rupture as we had just assumed it was another sebaceous cyst. I can’t stress this enough, please get all lumps checked on your senior dogs, especially if they’ve had allergies and hotspots all their lives.
I really hoped that I’d never have to put Winger down just because he was bleeding. I had hoped he’d be really sick and he’d tell me it was time, or even better, than he’d just pass in his sleep. Making the decision when to say good-bye to your best friend is absolutely gut-wrenchingly difficult. But once he passed, I knew I had done the right thing. His loud and constant panting and coughing was quiet. He looked so sweet, and gentle, and peaceful. The vet said he could tell he was really sick, as he went so fast.
I will miss him forever, my sweet sweet boy.

More about Winger

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